Action Research on Using Flipped Classroom Principles to Teach Upper High School Biology - Alexandra Kouloumbaritsi; Eva Dimitroglou; Evangelia Mavrikaki; Dia Galanopoulou ($\{upDelta}$$\upiota$$\upepsilon${\texttheta}$\upnu${\acuteε}$\upvarsigma$ $\{upSigma}$$\upupsilon$$\upnu${\acuteε}$\updelta$$\uprho$$\upiota$$\upomicron$ $\upgamma$$\upiota$$\upalpha$ $\uptau$$\upeta$$\upnu$ $\{upAlpha}$$\upnu$$\upomicron$$\upiota$$\up, 2016)